Iraqi forces on Tuesday pushed toward the river side of Mosul's Old City, their key target in the eight-month campaign to capture Islamic State's de-facto capital, and Iraq's prime minister predicted victory very soon.

Iraqi forces, battling up to 350 militants dug in among civilians in the Old City, said federal police had dislodged IS insurgents from the Ziwani mosque and were only a few days away from ousting militants completely from the Old City.

"The victory announcement will come in a very short time," Prime Minister Haider al-Abadi said on his website on Monday evening.